Solar thermal collectors are devices for converting sunlight into heat that can be used to perform work. They can fall into one or more categories including tracking (wherein the collector physically moves in order to follow the path of the sun to increase efficiency), non-tracking (wherein the collector does not track the path of the sun), and concentrating (wherein optics are used to concentrate the rays of the sun to increase performance).
One other characteristic of solar thermal collectors is their use of heat retention strategies to reduce heat loss to the environment to increase efficiency.